sqlparser: add tests to improve coverage

data/test/sqlparser_test/parse_pass.sql

@@ -82,7 +82,9 @@ select /* is not null */ 1 from t where a is not null
 select /* < */ 1 from t where a < b
 select /* <= */ 1 from t where a <= b
 select /* >= */ 1 from t where a >= b
-select /* <> */ 1 from t where a != b
+select /* > */ 1 from t where a > b
+select /* != */ 1 from t where a != b
+select /* <> */ 1 from t where a <> b#select /* <> */ 1 from t where a != b
 select /* <=> */ 1 from t where a <=> b
 select /* != */ 1 from t where a != b
 select /* single value expre list */ 1 from t where a in (b)

go/vt/sqlparser/ast_test.go

@@ -94,3 +94,15 @@ func TestLimits(t *testing.T) {
 		t.Errorf("got %v, want %s", err, wantErr)
 	}
 }
+
+func TestIsAggregate(t *testing.T) {
+	f := FuncExpr{Name: "avg"}
+	if !f.IsAggregate() {
+		t.Error("IsAggregate: false, want true")
+	}
+
+	f = FuncExpr{Name: "foo"}
+	if f.IsAggregate() {
+		t.Error("IsAggregate: true, want false")
+	}
+}